1. Field of the Invention
The present invention is directed to solder extracting type desoldering tools, and in particular, to such desoldering tools in which the extracted solder is collected in a disposable capsule.
2. Description of Related Art
In solder extracting type desoldering tools, a vacuum is used to draw the re-melted solder into the desoldering tool where it is collected in a solder collecting receptacle of one type or another. While, in some cases, a removable porous solder retention pad, liner or baffle has been provided to retain the collected solder in the collecting receptacle and/or to facilitate removal of the collected solder. An example of one such type of desoldering tool is described in U.S. Pat. Nos. 5,143,272 and 5,007,574 in which a tray like receptacle is a removable, but permanent, part of the tool and in which a removable porous solder retention pad is disposed. Among the short-comings of such desoldering tools are the facts that the tool can only be used in certain orientations and during use the suction flow path can become obstructed with solder and flux, thereby causing the suction force to fall off and the ability of the tool to extract solder is impaired as a result.
Substantially contemporaneous with the present invention, a desoldering tool was introduced by Weller under Model No. SCD-100 in which solder is collected in a disposable cylindrical capsule which is open at one end for receiving the extracted molten solder and is closed at the opposite end by a filter through which the solder extracting vacuum is drawn. To prevent the filter from immediately becoming obstructed by the extracted solder, a metal baffle is disposed within the capsule chamber for the purpose of causing the extracted to solder to solidify thereon. However, in practice, the baffle cannot predictably insure that the intended amount of solder is extracted before a vacuum failure occurs, i.e., sometimes the capsule is able to sufficiently fill with solder and other times vacuum failure might occur well before the capsule is adequately filled with extracted solder. Furthermore, the use of such baffles reduces the effective volume of the capsule to such an extent that a low volumetric efficiency is obtainable even under the best of circumstances, thereby causing the rise time (i.e., the time to reduce the pressure sufficiently to draw the solder up into the tool) to be longer than is optimally desirable. Additionally, since the capsule body is formed of the plastic material Kapton.RTM. (which has a usable temperature range of up to 800.degree. F.) and the baffle is made of a metal, such as stainless steel (with a melting point of around 2000.degree. F.), recycling of the extracted solder is not practical since it cannot be easily removed from the capsule, and the capsule and baffle cannot be burnt off at sufficiently low temperatures. Still further, exchanging of a filled capsule with new, empty one is not a simple process that can be performed quickly (which is essential in production facilities) since the capsule is hot, all of the extracted solder may not have solidified, and withdrawal of the capsule requires significant manipulation of the desoldering tool and the capsule itself.